...then obviously the film would end where we all assume it will from the new banner. But to my knowledge, Jackson has made no such announcement. If he had, all this discussion would be moot. The new banner was made by Warner Bros. and as such is not an "announcement" by Peter Jackson.

Again, this is just speculation designed to reconcile some seeming contradictions, and as such is probably wrong- it just always seemed strange to me to end the first film at that point, hence the theory that the banner / cast list changes may have been provisional. Don't mess with my favorite female elf.